Avian influenza virus circulation and immunity in a wild urban duck population prior to and during a highly pathogenic H5N1 outbreak

Abstract

Highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b viruses were first detected in St. John’s, Newfoundland, Canada in late 2021, with the virus rapidly spreading across the western hemisphere over the next year. To investigate the patterns of avian influenza virus (AIV) infection and immune responses subsequent to the arrival of H5N1, we sampled the wild urban duck population in St. John’s for a period of 16 months after the start of the outbreak and compared these findings to archived samples. Antibody seroprevalence was relatively stable before the outbreak (2011-2014) at 27.6% and 3.9% for anti-AIV (i.e., NP) and H5-specific antibodies, respectively. During the winter of 2022, AIV-NP and H5-specific antibody seroprevalence both reached 100%, signifying a population-wide infection event. As expected, population-level immunity waned over time, and we found that ducks were seropositive for anti- AIV-NP antibodies for around twice as long as for H5-specific antibodies. The population was H5 seronegative to the latter approximately six months after the initial H5N1 incursion. In late February 2023, H5N1 clade 2.3.4.4b viruses were again detected in the duck population as a result of a second incursion into Newfoundland from Eurasia, which resulted in a second population-wide infection event. We observed a clear relationship of increasing antibody levels with decreasing viral RNA loads that allowed for interpretation of the course of infection and immune response in infected individuals and applied these findings to two cases of resampled ducks to infer infection history. Our study highlights the significance of applying both AIV surveillance and seroprevalence monitoring to provide a better understanding of AIV dynamics in wild populations, which may be crucial following the arrival of 2.3.4.4b H5Nx subtypes to assess the threats they pose to both wild and domestic animals, and to humans.

Seabird and sea duck mortalities were lower during the second breeding season in eastern Canada following the introduction of Highly Pathogenic Avian Influenza A H5Nx viruses

“…These pre-migration staging areas, combined with cooling temperatures in the fall (i.e., conditions favourable for the virus, Webster et al 1992) likely facilitated the spread of the HPAI virus among Snow Geese in southern QC. The notable mortality event involving Canada Geese occurred later in the fall/winter period (March 2023), and this time of year birds can be more susceptible to infection due to colder winter temperatures, limited food availability, and generally lower body condition (Moon et al, 2007; Van Gils et al, 2007; Wight et al, 2024). The third notable mortality event involved at least 212 Northern Gannets reported on Bonaventure Island in October 2022.…”

Longitudinal Influenza A Virus Screening of Retail Milk from Canadian Provinces (Rolling Updates)

“…Any sample that tests positive for the matrix gene will be subsequently screened for the H5 subtype of the haemagglutinin gene also as per Wight et al . (34). In the event of positive sample identification, data will be immediately shared with federal agencies through existing linkages and collaborative connections.…”

“…Real-time RT-PCR was used to screen for the presence of IAV matrix gene RNA as per Wight et al (40) using a QuantStudio 6 Flex instrument (Applied Biosystems). Any sample that tests positive for the matrix gene will be subsequently screened for the H5 subtype of the haemagglutinin gene also as per Wight et al (40).…”

“…Real-time RT-PCR was used to screen for the presence of IAV matrix gene RNA as per Wight et al (40) using a QuantStudio 6 Flex instrument (Applied Biosystems). Any sample that tests positive for the matrix gene will be subsequently screened for the H5 subtype of the haemagglutinin gene also as per Wight et al (40). In the event of positive sample identification, data will be immediately shared with federal agencies through existing linkages and collaborative connections.…”